The present invention deals with the health hazard problem caused by the common disposable syringes when they are reused for self-administration by the users. The invention is particularly useful in preventing drug addicts from finding and using said disposable syringes for drug addiction purposes. These problems of current and worldwide interest were only partially solved by the self-nonreusable syringes of the above-mentioned patents since the user could intentionally and readily detach the self-destructing element from the syringe before using it, thereby permitting reuse. Some of these devices employed a puncturing pin attached to the syringe piston, which pin would puncture the bottom of the syringe to make it non-reusable after the completion of the injecting stroke of the piston. However, the resulting protruding pin could prick the fingers of the user, if he or she were not careful. Also in some instances the protruding pin could be extracted and the hole caused by it plugged so as to permit reuse of the syringe.
It is an object of the present invention to make the above devices more effective in insuring non-reusability of the disposable syringes, preferably, totally avoiding their possible reuse, even if the user would intentionally try to make the self-destructing element inoperable. It is a separate object to prevent the self-destructing element from accidentally causing harm to the user and also to make it more difficult to repair any break in the cylinder caused by a puncturing pin or the like.